[Clascomment] OPT-IN:First Measurement of the Polarization Observable E in the p(gamma, pi+)n Reaction up to 2.25 GeV

[Sebastian Kuhn]

Just a few comments:

1) I am a bit worried about this "kappa" parameter. It is not well explained, and it is quite huge! If I don't misinterpret something, you are saying that even after taking into account your best fit for the background, you needed to change the asymmetries by 30%? I would expect there to be a significant systematic error attached to that!

2) It might be nice to show some representative Mainz data (where they exist) together with your results.

3) There is some strange feature in Fig. 2 (at least in my browser) - there is a green line at the top edge of many panels. Probably a plotting glitch.

4) p. 3 line 10: The quoted value (< 0.015) is smaller than the one in line 8, yet your statement about "limited vertex resolution" would lead me to expect a LARGER uncertainty.

O.k., one more general comment: I realize that the article had to be short for PRL, but as the "first result from FROST", it contains rather little experimental detail (or even experimental results) and instead a bunch of fits. Unless these fits find something exciting, I'm not sure this warrants PRL publication. You hint at something interesting ("new evidence in the Bonn-Gatchina analysis for a poorly known reso- nance") - but then defer to a "follow-up letter", which could well be accused of as "serial publishing".